Art of centrifugal separation.



H. DE RAASLOFF & T. E. BROWN. ART OF CENTRIPIIGAL SEPARATION.

, 1910. RENEWED NOV. 5, 1912.

Patented Jan. 14, 1913.

APPLICATION FILED JUNE 30 ia-wow" UNITED STATES PATENT oEEio HARALD DERA ASLOEF AND THOMAS E. BROWN, 0]? NEW-YORK, N. Y.

'ART OF CENTR'IFUGAL SEPARATION.

Application filed June 30, 1910, Serial No. 569,631. Renewed November 5,1912.

and THOMAS E. BROWN, citizens of the United States, and residents oftheborough of Manhattan, in the county of New York and State-of NewYork, haye invented certain new and useful Improvements in the Art ofCentrifugal Separation, of which the following is a specification.

This invention relatesto improvements in the art of centrifugalseparation ofmaterials of different specific ravities.

The invention is applicable to the separation of materials of differentspecific gravities in all cases wherein at least one of the cable tocases in WlllGlltllB other material is also a liquid.

The essential step of theprocess is the,

generating, either through the centrifugal force'or through otheragencies, of a pressure in the mixture less than normal atmos.

pheric pressure. This low pressure is generated at a part of the vesselcontaining the mixture, which is nearer the axis of rotation of themixture than is the point at which .the' heavier concentrates aredischarged from said vessel; and said part is also nearer the said axisofrotation than is the part of said vessel in which the materials.Therefore, when, in the description or the claims, we use the termpoint,

I let for heavier material from the separating chamber or the part ofsaid chamber in which the heavier material concentrates. Moreover, for,brevity of description, we

frequently hereinafter designate the said reduced pressure in themixture by the term i vacuum, meaning thereby not necessarily anabsolute vacuum, butany pressure less than the contemporary normalatmospheric.

pressure outside of the apparatus in which the process is then beingoperated.

The process therefore, broadly speaking,

consists in revolving the mixture of the materials which are to beseparated, and at least one of which must be a liquid, around an axis ofrotation, whereby a centrifugal force is developed which impels theheavier Specification of Letters Patent.

heavier materials concentrate as they separate from the lighter PatentedJan. 14, 1913.

Serial No. 729,659.

material outwardly from the said axis, and separates, or at least tendsto separate, it from the lighter material. Simultaneously with thegenerating of the centrifugal force, a. pressure less than the normalatmospheric pressure is developed in a part of the mixture which isnearer the axis of rotation than is the point of concentration of theheavier material. The consequence of developing this reduced pressure atthis part is that the normal atmospheric pressure'acts upon -the lightermaterial. in a direction opposed to the direction of the centrifugalfOTC,tIld, thereby, to the degree due to the excess ;of the normalatmospheric pressure over said reduced pressure, prevents the lightermaterial from moving outward with the heavier material. To produce themost perfect separation the velocity of revolution of the mixtureis'limited so that the centrifugal force generated thereby in thelighter material is less than, or at least can never exceed the forcedue to, normal atmospheric pressure; and thereby the lighter materialsareperpetually restrained from flowing .out'

by the discharge outlet for the heavymaterials and reuniting with themafter the separation has once occurred. Finally the process includes theapplication of separate forces, independent of the centrifugal force, toremove the lighter and the heavier materials by different-outlets Theprocess can be carried out by many ditle-rent'apparatus, among whichare, for example, the apparatus ject of our application for UnitedStates Letters Patent filedMarch 16, 1909, Serial Number 483,670, andnow pending; and the process can also be carried out by various otherapparatus. The process is therefore hereinafter described, and theapparatus which is the sub-' not limited to any particular pparattelements, and we consider one aspect of our -i'rivention to broadlyconsistin the process as hereinbefore defined, however the apparatuswhich applies it may be constructed or arranged.

For the purpose of rendering the application of said process clear, wehereinafter describe it in connection with that form of apparatus whichwe prefer to use in connection with it, and We claim various parts andcombinations of parts of said apparatus in to the discharge pipe 30,causes it to circu- 65 adivisional application. late properly in saidchamber 25, and for a eferring to the drawings which accomtimesuflicient to effect the separation of the pany the specification, and,as hereinbefore heavier materials. Said i 30 is prefer- 5 stated,illustrated the preferred form of apably carried at an upwar'inclination to or paratus for applying the process, Figure 1 slightlyoutwardly beyond the line of at- 70 shows a vertical section andelevation, partly mospheric pressure, P-P, where said pipe broken away,of an apparatus in which the is trap ed, as shown at 32, and is o enedmixture is drawn n by suction from below. to atmosplieric pressure justwithin said at- 10 Fig. 2 is a broken horizontal section of onemospherlc line as at 33'. From said trap 32 of the separating chambers.a discharge pipe 31 leads down and dis- 75' eferring to said drawings,a,rotary pipe charges into the annular revolving recepor vessel 1 1srevolved at high speed b any tacle provided with a suitable dischargc.suitable means, as gears 2, 3 and pul ey 5, In order to produce a finalclarification of 15 from any source of power. Said pipe 1 is theseparated liquid, we prefer to place anpreferably supportedvertically insuitable nular filtering screens in said receptacle bearings 6, 7, whichmay be anti-friction 40, and to arrange said receptacle 40 to disballbearings. Said pipe 1 is closed at the charge into a lower stationaryannular retop 8, and its lower open end dips into theceptacle 68. Saidfiltering screens 60 are 20 materials to be separated in the vessel 20,to preferably composed of perforated metal which vessel they aredelivered in any suit rings a hacked by any suitable filterin maablemanner as by pipe2l, controlled by terial b. The outer end of each saidsepvalve 22. Said pipe 1 is connected by arating chamber is connectedwith suitable branches 24 with any desired number of sepmeans forremoving the concentrated 25 arating chambers 25, preferably arrangedheavier material as rapidly as the same is symmetrically around saidpipe 1;, and a formed; and the preferred device isillusshort distanceabove its junction with said trated in Fig. 1, and consists of arevoluble branches, said pipe 1 is closed as seen at 10. andreciprocating worm 43 in a worm cas- Below said branches is a controlvalve 12, ing 42. Said worm 43 may be all of uni- 30 preferably of longconical shape, seating on form pitch; or it may be of a plurality ofaseat in diaphragm 11. A valve stem 13, different pitches 'Fig. 1showing said suitably guided through the guides 16, 16,- is worm in twoparts, whereof the upper part pivotally connected by lever 18, fulcrumedmay have the greater pitch. Said worm casat 17, to a float 19, whichrises and falls ac-, ing 42 may be throughout of uniform diam- 35cording to the level of the contents of said eter or it may be ofgradually increasing receptacle 20; and the arrangement of the diametertoward its discharge end; and said parts is such that when the level ofsaid con worm and casing are preferably arran ed at tents rises saidvalve-12 opens, and when the an inclination upwardly and inward y, solevel of said contents falls said valve 12 that the discharge from theworm takes place 40 closes; and by reason of the gradually taperwithinthe said atmospheric line PP, and

mg shape of said valve 12 the opening and sothat the effect of said worm43 is to proclosing of sa'id valve is also gradual, and pel theconcentrates in a direction opposed perfect control of the-delivery ofthe mato that of the centrifugal force. Said worm terial to theseparating chambers 25, and of discharges into a annular receptacle 69.R0-

45 the vacuum, is attained. A check valve 14, tary -and reciprocatingmotion are imparted guided on stem 13 and opening upwardly to said worm43 in any suitable manner. may also be employed if desired.- The innerAs shown in the drawings, the worm shaft closed end of each of saidseparating cham- 44, is suitably guided through the revolving bers 25 isarranged at a short distance. outbracket 45, which is carried on thesleeve 50 side of the line of zeropressure z-2,and 46, and revolves withsaid pipe 1. Said each of said chambers is preferably relatively worm isdriven by beveled gear 47 meshing ection and provided with with beveledgear 48 carried on loose sleeve a contracted .outer end forming anozzle. 49, which sleeve is in turn driven with dif- Each of saidchambers 25 is also preferably ferent-ial velocity, by the gears 50. 51.A

' 55 provided with a partition 28 extending part square part of saidworm shaft 44 works of the length of said chamber 25. The saidlongitudinally through a square hole in said branch pipe 24 connectswith the chamber gear 47, but turns with said gear. Said on one side ofsaid partition 28, and the disworm 43 can thus reciprocate while beingrccharge for the lighter separated materials volved by said gear 47. Acam 52 carried 60 30 connects with said chamber '28 on the by said gear57, and properly formed, lifts other side of said partition, and withthe a rocker 53 pivoted at one end on said 12 top of said chamber 25, 29being a diffusing bracket 45, and having a fork at the other screen.Thus said partition 28 preyents the end which engages under the head 54of mixture from flowing directly from the inlet said worm shaft 44.Thus, at proper intervals, said worm 4:3 is moved endwise in thedirection for discharging the concentrates, and as the'said cam 52continues its revolving, the centrifugal force forces said worm in theopposite direction, thrusting the end of the worm into the concentrates,which then travel more or less up the said worm 43, as the same revolvesand are finally lifted up to the discharge outlet by the end-wise motionof said worm. Of course springs or other devices in additiontocentrifugal force could also be employed to force said worm into theconcentrates. The reciprocating of the worm, with or without theincreasing pitch, and with or without the gradually increasing diameterof the worm or the worm casing toward the discharge end, enables theworm to properly discharge materials of any quality or consistency, andwhether the concentrates are slimy, greasy, or granular and gritty. Saidworm shaft may be provided with a rotary cutter 70, to cut or scrape offthe ends of the mass of concentrates, as the same are forced upward bythe worm. We prefer to connect the outer ends of said separatingchambers with the worm casings 42 by short pipes 57,

H as indicated, in order to equalize the mixture in said chambers 25 andsaid worm cas1ngs 42, particularly when the plugsof concentrates are ofimpervious clayey materials.

The production of the -vacuum.It being understood that the machine isrevolved at such velocity that the centrifugal force at the point ofdischarge of the lighter ingredients will just balance atmosphericpressure, then we prefer to generate the vacuum in a part of eachseparating chamber which is nearer to the axis of rotation of themachine than is the pointlof discharge from the said chamber of theheavier ingredients, in the following manner: Suppose the separatingchambers and other parts of the machine to be full of the mixture, themachine being originally at rest and the valve 12 closed, said chambershaving outlets permitting the dischargeiof concentrates at the rate theyare formed. Now suppose the 'machine to be revolved at the determined velocity, valve 12 being still closed. Then the concentrates would formunder the influence of centrifugal force, and the plug of concentrateswould discharge, and there would be developed in part of said chamber 28and said branch 24 and pipe 1, a vacuum. Now suppose the valve 12 isopened a certain amount, mixture then enters through said valve 12 intosaid chal'nbers 25, and the several i'naterials discharge therefrom onlya the rate at which mixture enters through said valve 12, and manifestlythere will be a pressure lower than normal atmospheric pressure in thepa'rtof said chamber which is within the line where the heaviermaterials concentrate, and particularly there will be a pressure lowerthan atmospheric in the part of said chamber 25 which is nearer the axisof rotation than is the point of discharge of the heavier concentrates.Consequently the normal atmospheric pressure will develop aforce in thelight liquid opposed to the centrifugal force, and which prevents thelighter liquid from fiowing out with the heavier concentrate through thesame opening. Thus the development of a vacuum in a part of theseparating chamber nearer to the axis of rotation thereof than is thepoint of discharge of the heavier concentrates is an indispensable stepin our process of separation, and while we prefer to generate the vacuumthrough the centrifugal force due to the revolution of the machine, yetwe can develop said vacuum by means independent of the centrifugalforce, as by suitable suction pumps properly connected with the innerends of the separating chambers; and as hereinbefore stated ourinvention is not limited. to any particular means of producing saidvacuum.

The process as a wholalhe process as an entirety is operated in thefollowing manner; The apparatus having been suitably primed preferablywhen at rest, and the valve (or said valve 12 and check valve 14 if bothare used) being closed, thema chine is started up. The centrifugal forcecauses the excess liquid to overflow at trap 32, and a vacuum is formedin pipes l and 24, and part of chamber 25. The supply valve 22 is openedthe propenamount, the materials rise in receptacle 20, the float 19opens the valve 12, and adjusts the area of the orifice to suit thesupply admitted by said valve22, the atmosphere presses on the surfaceof the materials in said receptacle 20,' causes them to rise in pipe 1,and the centrifugal force projects the mixed materials into the chambers25, where the centrifugal force causes the heavier matters to moveoutwardly and concentrate in the outer partand the nozzles of saidchambers. At this point thc traps formed by the inward inclination ofthe worm casings 42 prevent the discharge of the saidheavierconcentrates by centrifugal force. Therefore'said concentratescontinue collecting at the outlets of said chambers and inlets of saidworm casings, until the proper motion of said worm 43 pushes the end ofsaid worm into the mass of concentrates, .and the rotation and theupward lengthwise motion of the worm-then discharge a mass ofconcentrates out of the upper end of said worm casing intosaidreceptacle (39. Thus another step in our complete process is the removalof the heavier concentrates by a force or forces, other than centrifugalforce. In the chamber 25, there is no tendency for violent evendischarge of vsaid liquid from said 1 the reciprocating Worm theconcentrates are slimy and slippery, with c'e'ntrateaand very soon afterthe machine V finally discharge mto 'chargedregularly and under controlby its threads of the worm,

'is' started up there takes place a regular discharge of theconcentrates into the said receptacle, '69;-the several motions of theorm :being so timed that the concentrates are removed at the rate atwhich they are formed. a

New having described our improvements we claim as our-invention.

mean time the lighter liquid material's flow gently, and withoutinjurious eddies, around said partition 28 from the branch 24 to thepipe 30, to the traps 32, and thence down by pipe 31 to the filteringreceptacle 40, being filtered through the filtering screen60, ahdreceptacle 68. Thus, by reason of the vacuum in part of said gushing-outof the lighter liquid from the other materials of different specificgraviseparating chambers, but there is a regular ties, and oneat leastof which Is a liquid, which consists in revolving the mixed mate- 'rialsand thereby generating centrifugal force in the mixture which throws theheavier material outward from the axis of rotation and tends. toseparate it from the lighter material, and simultaneously developing apressure lessthan atmospheric preschambers at the same rate as that atwhich the liquid is supplied to said chambers by said valve 12. In casean increased quan-' tity of mixture enters said receptacle 20, throughsome variation in the supply head, float 19 will rise and will openvalve 12 until the discharge through said valve 12 sure in the mixture,whereby the greater into the separating chambers equals the normalatmospheric pressure opposes the cf amount delivered by valve 22 toreceptacle fect of the centrifugal force on the lighter 20; and in casethe quantity of mixture supmaterial and prevents said lighter materialplied to said receptacle 20 by valve 22 de'- from moving outward along-with, said creases, float 19 will fall and valve 12 will heaviermaterial; I more or less close-until the supply admitted 2. The processof separating from each to the separating chambers equals the quanothermaterials of difl'erent specific gravi' tity delivered to saidreceptacle 20. Thus ties, and one at least of 'which is a liquid, allirregularities in the supply are compenwhich consists in revolving themixed matesated for, and the process continues without rials and therebygenerating centrifugal interruption, the concentrates being reforce in.the mixture which throws the moved at the rate at which they are formedheavier material outward from the axis of and by their own properoutlet, and the rotation and tends to separate it from the lighterliquid being, asit were, held incheck lighter material, andsimultaneously devely h excess f n rmal atm spheric presoping a pressureless than atmospheric pressure over that existing in the said part of vsure in the mixture, whereby the greater the separating chambers, andbeing d1snormal atmospheric pressure opposes the effect of thecentrifugal force on the lighter material and prevents said lightermaterial from moving outward along with said heavier material, andextracting the concentrated heavy material as the same is concent-rated.

proper outlet, separate from the outlet which the heavier concentratesare discharged,- and at the rate at which said liquidis delivered tosaid separating chambers.

he operation 0 the reciprocating charm-J11 connection with our saidprocess 3. The process of separating from each hereinbefore deothermaterials of different specific graviscribed is very useful, althoughnot i'ndis- .ties, one at least of said materials being a pensable.VVith-various materials of a gritty liquid, which consists in revolvingthe mixed nature the reciprocation, ofithe Worm may material and therebygenerating centrifugal be dispensed with, since a rotary worm, forcewhich throws the heavier material outwithout reciprocating, willproperly convey ward from the axis of rotation and tends to anddischarge such materials. But when separate it from the lightermaterial, simultaneously generating a pressure loss than atmosphericpressure in the sa d; mixture, wherebythe normal atmospheric pressureopposes the outward motionof the lighter material along with saidheavier material, and applying force independent of thecentrifugahforceto separately extract the concentrate'dheavier materialand the lighter material.

4. The

but little friction against the walls of the worm casing, it isnecessary to employ a reciprocating worm to efiect the proper dischargeof the concentrates. For such concentrates are liable to merely revolvewith the Worm in the casing and not to advance, unless the wormreciprocates. But. with our reciprocating worm, then, at properinter.-vals, the worm first pushes into the concentrates, which fill, more orless, a number of and then the upward motion of the worm lifts thecharge of conm s of separating from each other materials of differentspeclfic gravr 1. The processof separating from each Lnof'soyao 'forcewhich throws the heavier material outward from the axis of rotation andtends to separate it from the lighter material, siinultaneouslygenerating a pressure less than atmospheric pressure in the saidmixture, whereby the normal atmospheric. pressure opposes the outwardmotion of the lighter material along with said heavier material,applying force independent of the centrifugal force to separatelyextract the concentrated heavier material and the lighter ma terial, andclarifying the lighter material.

Signed at New York city in the county of New York and State of New Yorkthis 29th day of June A. D. 1910. M

HARALD DE RAASLOFF; THOMAS E. BROWN. Witnesses:

G. V. HOPKINS, WALTER N. HARRIS.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Iatents,

' Washington, D. G.

